Methods And Apparatus For An Extensible And Scalable Control Channel For Wireless Networks

ABSTRACT

Methods and apparatus to enable an extensible and scalable control channel for wireless networks. In one embodiment, an Enhanced Physical Downlink Control Channel (ePDCCH) is disclosed that is implemented with a flexible number of Physical Resource Blocks (PRBs). Advantages of the ePDCCH include, for example: more efficient spectral utilization, better frequency management across multiple serving entities (e.g., base stations and remote radio heads), and extensible payload capabilities that can scale to accommodate higher or lower control information payloads, as compared to prior art PDCCH solutions.

PRIORITY

This application claims priority to U.S. Provisional Patent ApplicationSerial No. 61/557,329 filed Nov. 8, 2011, entitled “METHODS ANDAPPARATUS FOR AN EXTENSIBLE AND SCALABLE CONTROL CHANNEL FOR WIRELESSNETWORKS”, which is incorporated herein by reference in its entirety.

COPYRIGHT

A portion of the disclosure of this patent document contains materialthat is subject to copyright protection. The copyright owner has noobjection to the facsimile reproduction by anyone of the patent documentor the patent disclosure, as it appears in the Patent and TrademarkOffice patent files or records, but otherwise reserves all copyrightrights whatsoever.

BACKGROUND OF THE INVENTION 1. Field of Invention

The present invention relates generally to the field of wirelesscommunication and data networks. More particularly, in one exemplaryaspect, the invention is directed to methods and apparatus for anextensible and scalable control channel for wireless networks.

2. Description of Related Technology

A cellular network operator provides mobile telecommunications servicesto a population of cellular user devices via a network infrastructure ofe.g., cellular base stations (BS), base station controllers,infrastructure nodes, etc. One important aspect of cellular networkoperation relates to the control and management of the networkresources. Within certain cellular technologies, a so-called “controlchannel” is dedicated to exchanging control information between thecellular base station, and the population of cellular user equipment.

Control channel design faces many challenges. In particular, a device isunaware of network operation until after the device has successfullydecoded the control channel. For this reason, prior art control channelshave allocated a pre-determined set of resources for control channeloperation. Thus, even if a mobile device has no other information abouta network, the mobile device can find the control channel based on theknown pre-determined set of resources.

However, while control channels are necessary for network operation,they reduce the amount of resources available for data transfer.Consequently, given the pre-determined nature of existing controlchannel implementations, existing networks are typically inefficient, asthe pre-determined control resources are purposely conservative, and notalways fully utilized.

Still further, due to the importance of control channel information,significant effort is spent ensuring that control channel information isaccurately received by the receiver. Existing solutions employ multiplecountermeasures to protect control channel delivery, including forexample robust coding schemes, and relatively higher transmission powerfor control channels. Unfortunately, these countermeasures alsocontribute to network under-utilization. For example, robust codingschemes are based on increasing redundancy (i.e., useful data is paddedwith redundant information); similarly, higher transmission power canincrease interference in other channels. Higher control channel poweralso can adversely impact battery longevity in e.g., mobile cellulardevices.

Accordingly, improved solutions for control channel operation withinexisting and future cellular networks is needed. Improved controlchannel operation would ideally: (i) increase control channel capacity,(ii) improve control channel scalability (iii) provide interferenceavoidance coordination, and (iv) reduce control channel overhead.

SUMMARY OF THE INVENTION

The present invention satisfies the aforementioned needs by providing,inter alfa, improved apparatus and methods for an extensible andscalable control channel for wireless networks.

In a first aspect of the present invention, a method of operating awireless network is disclosed. In one embodiment, the method includes:partitioning one or more frequency resources into a number of frequencypartitions, where each frequency partition contains one or more controlchannel regions; assigning one or more mobile devices to a correspondingone of the one or more control channel regions; and transmitting controlinformation associated with the assigned one or more mobile devices viathe corresponding one of the one or more control channel regions.

In one variant, each control channel region includes an integer numberof physically consecutive or logically consecutive physical resourceblocks. In one example scenario, each control channel region is assignedto one or more remote radio entities associated with a macro-cell. Inone such scenario, the device operates according to a time divisionduplex (TDD) scheme. Alternately, the device operates according to afrequency division duplex (FDD) scheme.

In another variant, the one or more frequency resources are furtherpartitioned according to a time interval. In one such variant, the timeinterval is a time slot. Alternately, the time interval is a subframe.

In another embodiment, the method includes: transmitting one or morecontrol channel regions having a capacity, where the one or more controlchannel regions are associated with a set of client devices; andresponsive to a change in a control channel overhead for the set ofclient devices, adjusting the capacity of the one or more controlchannel regions.

In one variant, the adjusted capacity includes expanding a frequencyrange of the one or more control channel regions. In another variant,the adjusted capacity includes expanding a time range of the one or morecontrol channel regions.

In one variant, the change in the control channel overhead includes achange to the population of client devices. Alternately, the change inthe control channel overhead includes a change to one or more messageformats.

In yet another embodiment, the method includes: partitioning one or morefrequency resources into a number of frequency partitions, where eachfrequency partition contains one or more control channel regions;transmitting a first control channel region via a first frequencypartition in a first geographic location; transmitting a second controlchannel region via the first frequency partition in a second geographiclocation; where the first and second geographic location are spatiallydistinct; and where the first and second control channel region share acommon cell identifier.

In one variant, the one or more frequency partitions are furtherpartitioned into one or more time partitions. In another variant, theone or more control channel regions include a plurality of physicalresource blocks (PRBs). In one such variant, the plurality of PRBs arefurther permuted and distributed to a population of one or more clientdevices.

In other variants, the first geographic location is serviced by a firstremote radio head (RRH), and the second geographic location is servicedby a second RRH.

In still another embodiment, the method includes: for a plurality oftime intervals: permuting one or more control information associatedwith one or more mobile devices over one or more resource blocks of acontrol channel region; and transmitting the permuted one or morecontrol information via the one or more resource blocks of the controlchannel region.

In one variant, the permuting is configured to maximize frequencydiversity for the one or more control information. Alternately, thepermuting is randomized.

In one variant, the control channel region has a frequency range whichis a subset of an entire frequency range. In an alternate variant, thecontrol channel region has a temporal range which is a subset of anentire temporal range.

In a fifth aspect of the present invention, a method of wirelessoperation is disclosed. In one embodiment, the method includes:partitioning one or more frequency resources into a number of frequencypartitions, where each frequency partition contains one or more controlchannel regions; assigning one or more mobile devices to a correspondingone of the one or more control channel regions; and beamforming one ormore control information transmissions associated with the assigned oneor more mobile devices via a plurality of antennas.

In one variant, the control information transmissions include one ormore reference signals specific to a corresponding one of the assignedone or more mobile devices.

In a sixth aspect of the present invention, a wireless transmitter isdisclosed. In one embodiment, the wireless transmitter includes: awireless interface, the wireless interface configured to communicatewith one or more mobile devices; a processor; and a non-transitorycomputer-readable apparatus having a storage medium with at least onecomputer program stored thereon, the at least one computer programconfigured to, when executed on the processor: associate one or moremobile devices with a corresponding one or more control channel regions;and transmit control information associated with the associated one ormore mobile devices via the corresponding one or more control channelregions.

In one variant, the wireless transmitter is a remote radio head (RRH)coupled to an external evolved Node B (eNB). In an alternate variant,the wireless transmitter is an evolved Node B (eNB).

In still other variants, the at least one computer program is furtherconfigured to partition one or more frequency resources into a number offrequency partitions, where at least one frequency partition containsthe one or more control channel regions. In another variant, the atleast one computer program is further configured to assign the one ormore mobile devices to a corresponding one of the one or more controlchannel regions.

In another variant, the one or more frequency resources are furtherpartitioned according to a time interval. In one such variant, the timeinterval is a time slot, or alternately, a subframe.

In a seventh aspect of the present invention, a wireless receiver isdisclosed. In one embodiment, the wireless receiver includes: a wirelessinterface, the wireless interface configured to communicate with one ormore base station devices; a processor; and a non-transitorycomputer-readable apparatus having a storage medium with at least onecomputer program stored thereon, the at least one computer programconfigured to, when executed on the processor: identify one or morecontrol channel regions associated with the wireless receiver,transmitted by the one or more base station devices; and decode controlinformation within the identified one or more control channel regions.

In one variant, the identified one or more control channel regionsincludes a frequency range which is a subset of an entire frequencyrange.

In another variant, the identified one or more control channel regionsincludes a temporal range which is a subset of an entire temporal range.For example, in one scenario the temporal range is a time slot.Alternately, the temporal range may be a subframe.

In one variant, the decoded control information includes one or morereference signals specific to the wireless receiver. In still othervariants, the identification of one or more control channel regions isbased on a message received from at least one of the one or more basestation devices.

Other features and advantages of the present invention will immediatelybe recognized by persons of ordinary skill in the art with reference tothe attached drawings and detailed description of exemplary embodimentsas given below.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a graphical illustration of the prior art Long Term Evolution(LTE) control channel structure.

FIG. 2A illustrates one exemplary Enhanced NodeB (eNB) and an array ofRemote Radio Heads (RRH) which are used to provide improved coverage fora population of User Equipments (UEs), useful in conjunction withvarious aspects of the present invention.

FIG. 2B is a graphical illustration of one embodiment of a structure forenhanced Physical Downlink Control Channel (ePDCCH) regions according tothe invention.

FIG. 2C is a graphical representation of one exemplary procedure forforming ePDCCH regions over a slot according to one embodiment of theinvention.

FIG. 3 is a graphical representation of the contents of the ePDCCHregion according to one embodiment of the invention.

FIG. 4 is a graphical representation of the structure of the physicalresource block according to one embodiment of the invention.

FIG. 5 is a graphical representation of the relative location of ePDCCHin time and frequency in backward compatible and non-backward compatiblecarrier types according to one embodiment of the invention.

FIG. 6 is a functional block diagram illustrating one embodiment of aclient or user device incorporating the enhanced control channelfunctionality of the invention.

FIG. 7 is a functional block diagram illustrating one embodiment of aserver device incorporating the enhanced control channel functionalityof the invention.

FIG. 8 is a functional block diagram illustrating one generalized methodfor dynamic allocation of resources for transmission of controlinformation within an extensible and scalable control channel of awireless network, according to various aspects of the present invention.

All Figures © Copyright 2012 Apple Inc. All rights reserved.

DETAILED DESCRIPTION OF THE INVENTION

Reference is now made to the drawings, wherein like numerals refer tolike parts throughout.

Detailed Description of Exemplary Embodiments

Exemplary embodiments of the present invention are now described indetail. While these embodiments are primarily discussed in the contextof a third generation UMTS wireless network (3G), and more specificallyin one variant to LTE (3.9G) and fourth generation LTE-A (4G) networks,it will be recognized by those of ordinary skill that the presentinvention is not so limited. In fact, the various aspects of theinvention are useful in any wireless network that can benefit fromextensible and scalable control channels for wireless networks describedherein.

As used herein, the term “wireless” means any wireless signal, data,communication, or other interface including without limitation Wi-Fi,Bluetooth, 3G (e.g., 3GPP, 3GPP2, and UMTS), HSDPA/HSUPA, TDMA, CDMA(e.g., IS-95A, WCDMA, etc.), FHSS, DSSS, GSM, PAN/802.15, WiMAX(802.16), 802.20, narrowband/FDMA, OFDM, PCS/DCS, analog cellular, CDPD,satellite systems, millimeter wave or microwave systems, acoustic, andinfrared (i.e., IrDA).

Furthermore, as used herein, the term “network” refers generally to anytype of data, telecommunications or other network including, withoutlimitation, data networks (including MANs, PANs, WANs, LANs, WLANs,micronets, piconets, internets, and intranets), satellite networks,cellular networks, etc.

Prior Art Physical Downlink Control Channel (PDCCH)

Referring now to FIG. 1, one illustration of the prior art Long TermEvolution (LTE) control channel structure 100 is shown. Each frame spans10 ms and, consists of ten (10) subframes (numbered #0 to #9); whereeach subframe consists of two (2) slots (numbered #0, #1); and each slotconsists of seven (7) OFDM symbols (numbered #0 to #6). The entire LTEbandwidth is split into N “sub-carriers” where N denotes the size of theFFT/IFFT. LTE data is transferred according to this time-frequency“resource grid”. As shown, the downlink control signaling is located atthe start of each downlink subframe, and may span up to the first three(3) OFDM symbols.

Downlink control signaling consists of three physical channels: (i) thePhysical Control Format Indicator Channel (PCFICH), (ii) the PhysicalHybrid-ARQ (Automatic Repeat Request) Indicator Channel (PHICH), and(iii) the Physical Downlink Common Control Channel (PDCCH). Each of theforegoing is described in greater detail hereinafter.

The PCFICH indicates the number of Orthogonal Frequency DivisionMultiplexing (OFDM) symbols (1, 2, or 3) used for control signaling inthis subframe. The PCFICH contains a codeword which corresponds to theappropriate length of the PDCCH. The PCFICH is mapped onto the firstOFDM symbol when present, however the PCFICH is only transmitted whenthe number of OFDM symbols for PDCCH is greater than zero.

The PHICH contains an acknowledgement (ACK) or non-acknowledgement(NACK) for uplink data transmission. PHICHs are located in the firstOFDM symbol of each subframe, and are sent four (4) subframes after theHARQ-ed transmission across several (for example, if an uplinktransmission occurs in subframe n, the corresponding PHICH will be insubframe n+4). A PHICH is carried by several Resource Element Groups(REGs); as a brief aside, each REG contains four (4) time-frequencyResource Elements (RE) and each RE corresponds to a specifictime-frequency unit defined by a subcarrier and a symbol. MultiplePHICHs can share the same set of REGs using orthogonal spreadingsequences as a so-called “PHICH group”. Each PHICH is identified by twoparameters: the PHICH group number, and the orthogonal sequence indexwithin the group.

The PDCCH carries the downlink scheduling assignments and uplinkscheduling grants for each UE. In slightly more detail, the PDCCH istransmitted on one or more consecutive Control Channel Elements (CCEs),where a CCE corresponds to a multiple of nine (9) Resource ElementGroups (REGs). Briefly, the PDCCH carries scheduling assignments andother control information in the form of Downlink Control Information(DCI) messages. Each DCI is generated based on a set of parameters thatincludes: the number of downlink Resource Blocks (RBs), the DCI format,etc. The DCI messages are processed (e.g., channel coded, scrambled,modulated, precoded, and mapped to complex symbols), and mapped ontoREs. The REGs/CCEs allocated for each downlink control signalingtransmission are composed of these resultant REs.

As previously mentioned, the control region of a subframe (e.g., thefirst one, two or three OFDM symbols spanning the entire frequency band)contains PDCCHs for multiple UEs, thus each UE has to monitor acomparatively large area to extract its own control information (whichis only a fraction of the entire control region). Since the UE does notknow ahead of time the control channel structure, the UE has to decodethe entire control region (the first three symbols of the entirespectral bandwidth). This imposes a substantial burden on the UE; thesignificant burden of control channel decoding increases the componentcomplexity (and cost), and also reduces the performance of the UE and tosome degree adds to battery drain.

More generally, the existing PDCCH structure was designed to providecontrol signaling and resource assignments for User Equipments (UEs)based on a single transmission point per macro-cell usage scenario.However, many usage scenarios have emerged which do not fall into asingle transmission point paradigm. Several of these scenarios aredescribed in greater detail hereinafter.

In one such example, significant research has been directed toCoordinated Multiple Point (CoMP) techniques that enable transmissionand reception of signals from multiple cell sites. In various CoMPscenarios, multiple cell sites can coordinate transactions. Forinstance, in so-called “CoMP scenario 4” (as described within 3GPP TR36.819 Technical Specification Group Radio Access Network; Coordinatedmulti-point operation for LTE physical layer aspects (Release 11)published September 2011, incorporated by reference in its entirety),several Remote Radio Heads (RRH) having the same physical CellIdentifier (Cell ID) are deployed within a single macro-cell. Existingimplementations of RRH can be considered geographically distinctantennas that are controlled by an eNB via a fiber (or other high-speeddata link). Since each RRH has the same Cell ID, the RRHs areindistinguishable from the eNB by the UE. Thus, each RRH provides avirtually identical radio interface at a different physical locationwhich results in improved physical coverage of the cell within an area.While CoMP scenario 4 provides improved coverage, CoMP scenario 4 doesnot provide any increase in capacity.

In another such example, within so-called “CoMP scenario 3”, each RRHhas a different Cell ID relative to the associated macro-cell. Since theeNB and RRHs share the same time/frequency resources but are no longerindistinguishable from one another, the eNB and RRH will interfere withone another causing significant intra-cell interference. Furthermore, inthe context of CoMP scenario 3, the resource assignments correspondingto each RRH are under control of the eNB; each assignment has to besimultaneously transmitted to the RRHs to ensure proper coordination.However, this control overhead causes a significant increase in thenumber of resource assignments, and reduces the number of availableControl Channel Elements (CCEs) per subframe. Thus, the requirements ofCoMP scenario 3 can significantly strain the limited capacity ofexisting PDCCH operation. Moreover, in this context, techniques fordetecting existing PDCCH structures in subframes with stronginterference may be unsatisfactory. Proposed solutions include, forexample, scheduling an Almost Blank Subframe (ABS) in one node to reduceinterference while other nodes are transmitting. Unfortunately, ABSschemes require the blanking network node to reduce its own activity(e.g., transmission power) in the ABS, which is very inefficient from aspectral utilization standpoint. As with CoMP scenario 4, CoMP scenario3 consumes significant control channel capacity.

Furthermore, several improvements have been made since the initial PDCCHdesign (PDCCH is described within 3GPP TS 36.300, “TechnicalSpecification Group Radio Access Network; Evolved Universal TerrestrialRadio Access (E-UTRA) and Evolved Universal Terrestrial Radio AccessNetwork (E-UTRAN); Overall description; Stage 2 (Release 11), publishedSeptember 2011, incorporated by reference in its entirety).Specifically, new transmission modes have been implemented or proposedbased on UE-specific reference signals that have been designed tosupport Multi-User Multiple Input Multiple Output (MU-MIMO). Forexample, it is anticipated that so-called “Transmission Mode 9” will bewidely used in future deployments (Transmission Mode 9 is describedwithin 3GPP TS 36,213 Technical Specification Group Radio AccessNetwork; Evolved Universal Terrestrial Radio Access (E-UTRA); Physicallayer procedures, published March 2012, incorporated by reference in itsentirety). Transmission Mode 9 enables seamless switching between SingleUser MIMO (SU-MIMO) and MU-MIMO. Unfortunately, the Downlink ControlInformation (DCI) format used with Transmission Mode 9 (i.e., DCI format2C) has a very large payload size. Since, the existing PDCCH structurehas a fixed format (only 1, 2, or 3 of the first OFDM symbols of asubframe), the PDCCH must operate with fewer resource assignments (i.e.,fewer CCEs per subframe) in order to support the large payloads of e.g.,DCI format 2C. Thus, existing PDCCH structures are poorly suited tohandle new payload structures and/or payload structures of significantsize.

Moreover, in certain environments, neighboring transmission nodes mayinterfere with each other. The existing PDCCH mechanisms in earlierreleases of LTE may not be sufficient for robust transmission of controlchannels in dense and diverse deployments. For example, the enhancementof MEMO performance through improved Channel State Information (CSI)feedback for high priority scenarios is not directly targeted by thefeedback enhancements in 3 GPP TS 36.213 Technical Specification GroupRadio Access Network; Evolved Universal Terrestrial Radio Access(E-UTRA); Physical layer procedures, published March 2012 incorporatedby reference in its entirety. In fact, scenarios where multiple (e.g.,four (4)) transmit antennas operate in a cross-polarized configurationhave yet to be studied in homogeneous and heterogeneous scenarios. Whileit is currently not known whether existing solutions can providesufficient performance, it is likely that current solutions provideinadequate interference avoidance coordination.

Furthermore, due to capacity limits of existing PDCCH structures, somedata resources may not be timely allocated. For example, existing PDCCHstructures use a hashing function to map CCEs within the so-called“control region”. Those of ordinary skill in the related arts willrecognize that a hashing function does not guarantee unique mappings,and in some cases two or more candidate sets can collide. Theprobability of collision is further exacerbated when UEs chooseaggregation levels greater than one. During collisions, the number ofassignments that can be transmitted on the PDCCH are limited (i.e., onlythe one of the candidate sets is transmitted), which reduces the overalluser throughput and increases the overall transmission latency.

Additionally, existing PDCCH structures were designed based on anassumed single frequency partition in each slot/subframe with afrequency reuse factor of one. Colloquially, this is known as “hard”frequency partitioning. In contrast, “soft” frequency partitioningschemes can be dynamically changed in software to adjust to differentpartitioning schemes and accommodate different frequency reuse schemes.Hard frequency partitioning cannot be used with Fractional FrequencyReuse (FFR) techniques. FFR in conjunction with soft frequencypartitioning can be used to mitigate interference, resulting in improvedrobustness and reliability of control and data signaling. Furthermore,use of frequency division multiplexing of data and control regions wouldallow for finer power control for each channel.

Still further, existing PDCCH operation relies on Cell-specificReference Signals (CRS) for channel estimation and coherent detection.Empirically, CRS schemes require significant overhead (e.g., the CRSdoes not contain any useful information and is broadcast at significantpower) and are ineffective for certain applications (e.g., closed-loopprecoding techniques, beamfoiiiiing and Multi-User Multiple InputMultiple Output (MU-MIMO)).

Finally, existing PDCCH operation is based on a resource allocationgranularity of one, two, or three OFDM symbols for the PDCCH. Each OFDMsymbol consumes approximately 7% of network overhead; this resourceallocation granularity is quite large, and contributes to an excessiveamount of wasted resources.

Existing solutions for LTE PDCCH have significant limitations,including: (i) limited capacity, (ii) limited payload capabilities,(iii) inadequate interference avoidance coordination, (iv) poor userthroughput, (v) insufficient frequency reuse capabilities, (vi) nobeamforming capabilities, and (vii) excessive overhead. Accordingly, animproved extensible and scalable solution for control channel operationwithin existing and future cellular networks is needed.

“Enhanced” Physical Downlink Control Channel

In view of the deficiencies of the existing PDCCH structure, new andimproved solutions for an Enhanced Physical Downlink Control Channel(ePDCCH) are desired.

Ideally, an improved ePDCCH should exhibit one or more of the followingattributes: (i) support increased control channel capacity, (ii) supportfrequency-domain Enhanced Inter-cell Interference Coordination (eICIC),(iii) achieve improved spatial reuse of control channel resource, (iv)support beamforming and/or diversity, (v) operate on new carrier typesand support future enhancements to physical layer features such as e.g.,

Multicast Broadcast Single Frequency Networks (MBSFN) subframes (seee.g., 3GPP TS 36.211 Technical Specification Group Radio Access Network;Evolved Universal Terrestrial Radio Access (E-UTRA); Physical Channelsand Modulation (Release 10), published March 2011 incorporated byreference in its entirety), (vi) coexist on the same carriertechnologies with legacy UEs, and/or (vii) use frequency-selectivescheduling to mitigate inter-cell interference.

Accordingly, in one exemplary embodiment of the present invention, anePDCCH region is defined in the time and frequency domain. Unlike priorart PDCCH channel structures which are limited to the first few symbolsof each subframe and transmitted over the entire spectral bandwidth of acell, in one variant the inventive ePDCCH is distributed throughout thespectral bandwidth according to a frequency, time, and/or transmitter.In one such variant, each Remote Radio Head (RRH) is allocated an ePDCCHregion that is defined according to according to a set of one or moreenhanced CCE (eCCE), where each eCCE is further encapsulated within asingle Physical Resource Block (PRB) in each slot/subframe. Eachexemplary PRB consists of twelve (12) consecutive subcarriers for asingle slot. Moreover, each RRH is associated with a subset of the usersof the cell; thus each ePDCCH region can be reduced to only the spectralresources necessary to serve the subset of users associated with theRRH.

As a brief aside, a PRB is the smallest granularity of spectralresources that an exemplary LTE evolved NodeB (eNB) can schedule.Depending on the size of the eCCE, there may be one or more eCCEs withina PRB. As described in greater detail hereinafter, this configurablestructure enables, inter alia, frequency division multiplexing of ePDCCHwith other channels such as e.g., Physical Downlink Shared Channels(PDSCH). For example, PDSCH can advantageously be interleaved intospectral bandwidths that are unused by the ePDCCH (and vice versa).

Additionally, the flexible eCCE structure can accommodate multiple DCIformats which are necessary to support current and future applicationsand enhanced modes (e.g., Multiple Input Multiple Output (MIMO), etc.).Furthermore, the resource blocks used for ePDCCH may be permuted andallocated in a localized or distributed manner to exploit frequencydiversity gain.

In one exemplary variant, Demodulation Reference Signals (DM-RS) areexclusively used for channel estimation and coherent detection withinresource blocks assigned to a particular user. By removing the relianceon Cell-specific Reference Signals (CRS) for channel estimation andcoherent detection, various embodiments of the present invention can befurther leveraged with MU-MIMO and beamforming schemes for providingePDCCH. Specifically, the UE can adjust reception according to existingDM-RS signaling according to existing beamforming techniques. Using thebeamforming weighting vectors, the UE can receive ePDCCH from theserving BS. The ability to receive a beamformed ePDCCH greatly improvesnetwork reliability and coverage.

Moreover, in one backward compatible variant, the ePDCCH can be furthersubdivided into an “even-region” and an “odd-region”. The even-regionePDCCH shares the even numbered slots with legacy PDCCH formats. Theodd-region ePDCCH occupies the odd numbered slots. This configurationensures backward compatibility and legacy support while introducing anew frequency division multiplexed (FDM) control structure.

In one such embodiment, the search spaces (both common and UE specific)of the Release 11 UEs is separated from those of earlier releases. Thisallows independent operation of Release 11 UEs and eNBs in so-called“green-field” deployments (i.e., where no previous networkinfrastructure has been deployed) without depending on legacyconfigurations, which results in lower overhead.

Additionally it will be appreciated, that similar (if not identical)structures can be used for time division duplexing (TDD) and frequencydivision duplexing (FDD) networks. This dual natured structure forePDCCH in TDD and FDD operation can reduce the cost and complexity ofmulti-mode devices.

Finally, since some networks have favored small-sized cells andsmall-range dense deployments, some variants may use higher modulationorders such as 16QAM (Quadrature Amplitude Modulation) for basebandprocessing of the control channels. Specifically, the lower path lossand higher operational SINRs (Signal to Interference plus Noise Ratios)enabled by various aspects of the present invention are particularlywell suited to small and dense cell deployments, although by no meanslimited thereto.

One exemplary embodiment of an Enhanced Physical Downlink ControlChannel (ePDCCH) structure that satisfies the current expectations whilealso remaining extensible and scalable for future improvements andmodifications is now described in greater detail herein. FIG. 2Aillustrates one exemplary Enhanced NodeB (eNB) 202 and an array ofRemote Radio Heads (RRH) 204 which are used to provide improved coveragefor a population of User Equipments (UEs) 206. As shown, each RRHprovides a small area of coverage which augments the cell that isprovided by the eNB. However, it is important to note that the coveragearea for each RRH (˜100 ft) is significantly smaller than the range ofthe cell (e.g., up to a mile).

FIG. 2B illustrates one high-level conceptualization of the exemplaryePDCCH structure and design 250. The frequency resources in each slot(or subframe depending on the desired time-domain granularity and thechoice of Transmission Time Interval (TTI)) are partitioned into anumber of Frequency Partitions (FP), where each frequency partitioncontains one or more ePDCCH regions. Each ePDCCH region consists of aninteger number of physically consecutive (localized) or logicallyconsecutive (distributed) physical resource blocks (PRBs). Each ePDCCHregion may be assigned to one or more Remote Radio Heads (RRH)associated with a macro-cell.

As shown in FIG. 2B, the ePDCCH regions 252 are located in the same ordifferent frequency partitions 254. In one exemplary embodiment, thepartitioning of frequency resources is flexible and can be dynamicallyconfigured, e.g., the frequency resources may change over time based ona cell-specific, semi-static or dynamic pattern. The ePDCCH regions arelocated in predetermined (configurable) frequency partitions and thebeginning of each region is calculated based on a frequency offset (FO)256 from the reference location.

Referring now to FIG. 2C, the exemplary procedure 260 for forming thefrequency partitions and the ePDCCH regions is illustrated. At step 262of the method 260, the PRBs are permuted over the entire availablesystem bandwidth to exploit frequency diversity gain. The permuted PRBsare regrouped and form frequency partitions FP₀ to FP_(K) (step 264).The number of frequency partitions is configurable and depends on thenetwork deployment parameters and topology. At step 266, a second-levelpermutation may be applied to the PRBs within each frequency partitionto further exploit frequency diversity gain. Once the PRBs have beenevenly distributed over the spectral bandwidth, at step 268 the permutedPRBs within each partition can be divided into one or more ePDCCHregions. The grouping and the number of ePDCCH regions depend on thenumber and the relative position of the RRHs that may or may not sharethe same cell ID within a macro-cell. In one exemplary embodiment, RRHswhich are in close proximity to one another will have different ePDCCHregions to minimize ePDCCH interference.

FIG. 3 illustrates one exemplary ePDCCH region in further detail. Asshown, each ePDCCH region 302 contains one or more ePDCCH 304corresponding to the UEs that are served by the eNB (e.g., ePDCCH1corresponds to UE1, ePDCCH2 corresponds to UE2, etc.). The location ofthe ePDCCH regions and individual ePDCCH channels are coordinated acrossneighboring eNBs to reduce the inter-cell interference (e.g., acrossmultiple eNBs, ePDCCH allocations for each eNB are scheduled so as tominimize collision with neighboring eNBs). Within each cell, the eNBcoordinates the ePDCCH regions corresponding to Remote Radio Heads(RRHs) managed within a cell. Each ePDCCH is mapped to a number ofenhanced Control Channel Elements (eCCEs) 306 depending on the desiredaggregation level. One or more eCCEs are mapped to one or more PRB 308.

FIG. 4 illustrates one exemplary structure of a Physical Resource Block(PRB) including Demodulation Reference Signals (DM-RS). As shown, theexemplary PRB 402 is 12 sub-carriers by 7 symbols. For an exemplary eCCEof 36 sub-carriers (or alternatively resource elements), the exemplaryPRB (which consists of 84 resource elements) can hold up to two eCCE. Asshown, the Demodulation Reference Signal (DM-RS) locations are based onone exemplary scenario where the same Orthogonal Cover Code (OCC) isused for multiplexing of two DM-RS corresponding to two transmitantennas. Higher order antenna configurations will include more DM-RSsignals to support e.g., beamforming of the UE-specific controlchannels. Specifically, higher order antenna configurations can useadditional DM-RS to create sharper and/or more complex beam footprintsby adjusting the antenna powers to constructively interfere (i.e.,within the beam footprint), and destructively interfere (i.c., out ofthe beam footprint). Moreover, where multiple eCCE are aggregatedtogether (where multiple eCCEs are grouped for an ePDCCH), theaggregated eCCE units may be mapped to different PRBs to ensure maximaluse of frequency diversity.

Referring now to FIG, 5, two exemplary configurations (500, 550) areillustrated, the first configuration 500 remains compatible with legacyequipment, and the second configuration 550 is incompatible with legacyequipment. Since user traffic is allocated in PRB pairs over a subframe,in consideration for downlink link budget, the ePDCCH may or may notexist in each downlink slot. For smaller cell size variants, theexisting minimum transmission time interval (TTI) of 1 ms may be furtherreduced to 0.5 ms (one slot). This shorter TTI further reduces theuser-plane and control-plane latency and increases the spectralefficiency. In such variants, an ePDCCH is required for each downlinkslot, enabling resource allocations on a slot-by-slot basis. Moreover,it is recognized that this structure is the same for TDD and FDD duplexschemes. For example, depending on the TDD frame configuration mode, theePDCCH can be transmitted in the downlink slots (or subframes) similarto that of FDD systems.

Referring now to the first configuration 500, each subframe is splitinto an even and an odd slot. During the even slot, the legacy PDCCH istransmitted, and ePDCCH. During the odd slot, ePDCCH can be transmitted.It is appreciated that a legacy device can decode the legacy PDCCHnormally within the first configuration; however, in addition enhanceddevices can decode ePDCCH in accordance with various aspects of thepresent invention. Moreover, it should be appreciated that the amount ofinformation provided via the legacy PDCCH can be greatly reduced to onlythe information necessary to service legacy devices, and enhanceddevices can rely primarily on the ePDCCH. Furthermore, since the DPCCHhas relatively large granularity (e.g., 7%), it is appreciated that asubset of enhanced devices may receive information via the PDCCH tofully utilize allocated PDCCH resources (as opposed to receivinginformation via a ePDCCH, while allocated PDCCH resources are leftunused).

In contrast to the first configuration 500, the second configuration 550relies solely on ePDCCH for control information signaling. Operation ofthe second configuration requires either a population of enabled userdevices, or alternately that legacy devices are precluded from access,or combinations thereof. In some variants, operation of the secondconfiguration may be offered in tandem with a secondary bandwidthspecifically to service legacy devices only (i.e., a first bandwidth isprovisioned for enabled users and a second bandwidth is provisioned forlegacy users).

In comparison to prior art PDCCH structures, the ePDCCH isadvantageously much more flexible and scalable. For example, the eDPCCHcan support control signaling and resource assignments from multipletransmission points within macro-cell deployments. Consider CoordinatedMultiple Point (CoMP) scenario 3 and CoMP scenario 4 operation(described supra) in conjunction with ePDCCH operation according tovarious aspects of the present invention; each RRH may transmit ePDCCHassignments without interfering with other RRHs, because theircorresponding ePDCCH's time frequency resources are not shared amongneighboring RRHs (i.e., neighboring RRHs are assigned to differentePDCCH regions). Since each RRH does not interfere with its neighborRRHs, interference avoidance coordination can be handled much moreeffectively via extant interference mitigation. Specifically, since theneighbor RRHs only contribute unrelated interference, theirtransmissions can be treated effectively as uncorrelated noise.

Similarly, arbitrarily large payloads can be accomodated by allocatingmore eCCE where necessary. This flexible payload capability canaccommodate larger format DCIs (e.g., Transmission Mode 9, etc.).Moreover, since the size of ePDCCH regions can be larger (or smaller),collisions across different cells and inter-cell interference can bemore effectively and flexibly mitigated]

Furthermore, the ePDCCH can accommodate multiple frequency partitions tosupport e.g., soft frequency partitioning and/or Fractional FrequencyReuse (FFR) techniques. Specifically, the ePDCCH can be flexiblyallocated across various PRBs to support various frequency allocationsincluding e.g., several soft and configurable frequency partitions ineach slot/subframe and frequency division multiplexing of control anddata regions. Frequency division multiplexing of data and controlregions allow for separate power control for each channel type.

Moreover, various embodiments of the ePDCCH perform channel estimationand coherent detection via Demodulation Reference Signals (DM-RS) whichare specific to a subscriber device, thus mitigating many of theinefficiencies of Cell-specific Reference Signals (CRS) based schemes(which are uniform for the entire cell and are not user specific).Additionally, the use of DM-RS (instead of CRS) is necessary to enablebeamforming of control channels; in particular, user specific DM-RS canbe configured on an antenna-by-antenna basis, to create a beamformedtransmission. There is no such benefit to beamforming CRS which iscell-specific and used across the entire cell.

Finally, control channel overhead for a PRB-based ePDCCH can be muchmore efficient than prior art solutions. For example, prior artsolutions reserve one or more OFDM symbols over the entire systembandwidth which consumes approximately 7% of overall system bandwidthfor each OFDM symbol. In contrast, the resource allocation granularity(L1/L2 overhead per PRB) in the exemplary implementations of theinvention is 2% for a 10 MHz system, and only 1% in a 20 MHz system.

Other Scenarios

Moreover, those of ordinary skill in the related arts will furtherrecognize, given the contents of the present disclosure, that variousaspects of the present invention are further useful in otherapplications. For example, in Carrier Aggregation (CA) based EnhancedInter-cell Interference Coordination (eICIC) and heterogeneous networks,the ePDCCHs of macro nodes and low-power nodes can be transmitted ondifferent component carriers. As a brief aside, CA allows a network toprovision large chunks of bandwidth by aggregating multiple smallerbandwidths.]. Thus, in one exemplary embodiment, cross-carrierscheduling can be provided for the CA-enabled UEs. In cross-carrierscheduling, the ePDCCH is provided in a first carrier, and providesinformation regarding the operation of a second carrier of a CA system.In one variant, the ePDCCH resources on the cross-scheduled carrier arelimited (thus the cross-scheduled carrier maintains some resources forits own traffic operation, etc.). In some further variants, the ePDCCHresource limitation can be adjusted to depend on the number of UEsconfigured with carrier aggregation in CA-based heterogeneous networks.

In another such example, inter-band carrier aggregation functionalityincludes scenarios where a lower frequency band is aggregated with ahigher frequency band. Typically, larger coverage is achieved on thelower frequency band due to desirable propagation loss resistance oflower frequency bands. Accordingly, it is possible to increase thetraffic channel coverage on the higher frequency band throughcross-carrier scheduling from an ePDCCH on the lower frequency band.Specifically, unlike prior art solutions which use a fixed allocationfor providing the PDCCH, the ePDCCH can be flexibly allocated withinvarious frequency bands.

In yet other examples, additional carrier types can be supported infuture systems (e.g., Release 11). For example, future releases may notbe backward compatible; i.e., legacy PDCCH may not be transmitted onfuture spectrum. Without further enhancements in the downlink controlchannels, the PDSCH/PUSCH channels on the non-backward compatiblecarriers may only rely on cross-carrier scheduling from a backwardcompatible carrier. Given that the bandwidth and the number of UEsconnected to the non-backward compatible carriers can be similar tobackward compatible carriers, the PDCCH resource on the cross-carrierscheduling carrier (i.e., where PDCCH is sent) can be significantlylimited. By providing more flexibility with an ePDCCH, future releasesare no longer limited to cross-carrier scheduling from backwardcompatible carriers.

Various enhanced MIMO modes can also be supported with the new ePDCCHstructure. The new ePDCCH substantially improves the robustness of thecontrol channels and thus mitigates the interference among neighboringtransmission nodes in dense and diverse deployments. Consequently, theePDCCH structure allows interference avoidance/coordination byorthogonalizing the UEs in neighboring cells. Additionally, CoMPscenarios 3 and 4 will benefit from the ePDCCH structural flexibility,and capacity. Downlink control enhancement for carrier aggregation isprimarily used in scenarios where cross-carrier scheduling is applied.The number of UEs configured with cross-carrier scheduling in eachcarrier aggregation scenario will determine whether ePDCCH is needed tosupport carrier aggregation scenarios.

In Release 8, Release 9 and Release 10, the control region of the PDCCHonly supports transmit diversity transmission mode. The transmitdiversity scheme is a robust transmission scheme but the efficiency maynot be as good as beamforming based on spatial information especially incorrelated environment. Unfortunately, increasing the number of transmitantennas may not yield higher MIMO gain for transmit-diversity-basedPDCCH transmission, in fact in some preliminary testing transmitdiversity actually results in performance degradation in some scenarios.Various embodiments of the present invention support beamforming whichshould further improve coverage.

Finally, in Release 8, Release 9 and Release 10, PDCCH only supportsQPSK modulation. The ePDCCH should significantly improve link quality(e.g., due to precoding/beamforming), thus, ePDCCH should also supporthigher order modulation in high SINR region. Higher order modulationwill increase the spectral efficiency, and reduce overall systemoverhead of control channel. In small-cell and dense deployments wherethe SINR is higher, ePDCCH can support higher order modulation (e.g.,16QAM) for the control channel.

Exemplary User Equipment (UE) Apparatus

Referring now to FIG. 6, exemplary client or UE apparatus 600 useful inimplementing the methods of the present invention is illustrated. Asused herein, the terms “client” and “UE” may include, but are notlimited to cellular telephones, smartphones (such as for example aniPhone™), personal computers (PCs), such as for example an iMac™, MacPro™, Mac Mini™ or MacBook™, and minicomputers, whether desktop, laptop,or otherwise, as well as mobile devices such as handheld computers (e.g.iPad™), PDAs, personal media devices (PMDs), such as for example aniPod™, or any combinations of the foregoing. The configuration ofcontrol channel reception is preferably performed in software, althoughfirmware and/or hardware embodiments are also envisioned; this apparatusis described subsequently herein with respect to FIG. 6.

The UE apparatus 600 includes a processor subsystem 605 such as adigital signal processor, microprocessor, field-programmable gate array,or plurality of processing components mounted on one or more substrates608. The processing subsystem may also include an internal cache memory.The processing subsystem 605 is connected to a memory subsystem 607including memory which may for example, include SRAM, flash and SDRAMcomponents. The memory subsystem may implement one or a more of DMA typehardware, so as to facilitate data accesses as is well known in the art.In the illustrated embodiment, the processing subsystem additionallyincludes subsystems or modules for implementing the enhanced controlchannel functionality described previously herein. These subsystems maybe implemented in software or hardware which is coupled to theprocessing subsystem. Alternatively, in another variant, the subsystemsmay be directly coupled to the digital baseband.

In one exemplary embodiment, the UE is additionally configured toidentify control information regions according to one or morepredetermined schemes. In some embodiments, the client device may berequired to try decoding multiple “hypotheses” to determine the locationof control channel information. For example, a UE may be configured toidentify one or more physical resources containing or likely to containcontrol channel information. While it is undesirable to blindly searchfor control regions, searching a small set of hypotheses cansignificantly reduce network coordination requirements without undueperformance losses in the UE operation. It will be appreciated, however,that the apparatus may also use external or provided information to helpidentify the control information regions of interest.

In one exemplary embodiment, the UE is configured to determine thecontrol region according to a flexible frequency partitioning. In onesuch variant, the frequency partitioning is dynamically configured,e.g., the resources may change over time based on a cell-specific,semi-static or dynamic pattern. In other variants, the frequencypartitioning is fixed but distinct for each transmitter. For example, incell-specific schemes the UE may be able to determine the control regionaccording to the particular cell identifier it is connected to (e.g.,the control region is selected based on a hash function based on thecell identifier, etc.). It is further appreciated that the controlregion may be applicable for only a subset of a cell; for instance,Remote Radio Head (RRH) may only provide enough coverage for a subset ofthe entire cell.

In still other embodiments, it is appreciated that the configurabilityof the control channel structure previously described enables dynamicdecoding based on resource, usage, and/or network considerations. Forinstance, a UE could decode various elements of the ePDCCH to supportcertain applications or operations and/or disregard other elements ofthe ePDCCH for unnecessary applications or operations.

Various other aspects of the present invention are readily appreciatedby those of ordinary skill in the related arts.

Exemplary Base Station (BS) Apparatus

Referring now to FIG. 7, exemplary server or base station (BS) apparatus700 useful in implementing the methods of the present invention isillustrated. As used herein, the terms “server” and “BS” include, butare not limited to base stations (e.g., NodeB, eNodeB, etc.), accesspoints, relay stations, etc. The configuration of control channeltransmission is preferably performed in software, although firmwareand/or hardware embodiments are also envisioned; this apparatus isdescribed subsequently herein with respect to FIG. 7.

The BS apparatus 700 includes a processor subsystem 705 such as adigital signal processor, microprocessor, field-programmable gate array,or plurality of processing components mounted on one or more substrates708. The processing subsystem may also include an internal cache memory.The processing subsystem 705 is connected to a memory subsystem 707including memory which may for example, include SRAM, flash and SDRAMcomponents. The memory subsystem may implement one or a more of DMA typehardware, so as to facilitate data accesses as is well known in the art.In the illustrated embodiment, the processing subsystem additionallyincludes subsystems or modules for implementing the enhanced controlchannel functionality described previously herein. These subsystems maybe implemented in software or hardware which is coupled to theprocessing subsystem. Alternatively, in another variant, the subsystemsmay be directly coupled to the digital baseband.

In one exemplary embodiment, the BS is additionally configured totransmit one or more dynamically configurable control informationregions according to one or more predetermined schemes. In somevariants, the dynamically configurable control information regionsaugment existing legacy schemes for control information regions. Inother variants, the dynamically configurable control information whollysupplants the legacy control information regions; these regions can beconfigured and/or signaled by the network to assist in fasteracquisition.

In one exemplary embodiment, a user equipment (UE) is configured todetermine the control region according to a flexible frequencypartitioning. In one such variant, the frequency partitioning isdynamically configured, e.g., the resources may change over time basedon a cell-specific, semi-static or dynamic pattern. In other variants,the frequency partitioning is fixed but distinct for each transmitter.For example, in cell-specific schemes the UE may be able to determinethe control region according to the particular cell identifier it isconnected to (e.g., the control region is selected based on a hashfunction based on the cell identifier, etc.). It is further appreciatedthat the control region may be applicable for only a subset of a cell;for instance, Remote Radio Head (RRH) may only provide enough coveragefor a subset of the entire cell.

In still other embodiments, it is appreciated that the configurabilityof the control channel structure previously described enables dynamicdecoding based on resource, usage, and/or network considerations. Forinstance, a UE could decode various elements of the ePDCCH to supportcertain applications or operations and/or disregard other elements ofthe ePDCCH for unnecessary applications or operations. In yet otherembodiments, the UE is configured to identify one or more physicalresources containing or likely to contain control channel information.For example, the UE may attempt to decode multiple “hypotheses”; whichit is undesirable to blindly search for control regions, searching asmall set of hypotheses can significantly reduce network coordinationrequirements without undue burden on the UE. Specifically, the networkhas some flexibility in providing control information to resolve e.g.,resource contentions, network congestion, network expansion, etc.

Various other aspects of the present invention are readily appreciatedby those of ordinary skill in the related arts.

Method

Referring now to FIG. 8, one embodiment of a generalized method 800 fordynamic allocation of resources for transmission of control informationwithin an extensible and scalable control channel of a wireless networkis illustrated and described.

In one aspect of the present invention, the extensible and scalablecontrol channel of the wireless network is based on a frequency divisionmultiplexing (FDM) scheme. Specifically, each control region isdemarcated according to a relevant frequency range. Moreover, asbandwidth increases or decreases, the control regions can be expanded,or contracted accordingly. In alternate embodiments, the control regionmay be based on a time division multiplexing (TDM) scheme, where eachcontrol region is specified according to a relevant time range.

In a second aspect of the present invention, the control regions arespatially distributed so as to reduce interference with one anotherwithin the same cell. For example, consider a cell having multiple RRHs;each RRH can be assigned to a control region so as to minimizeinterference with its neighboring RRHs (for an FDM based scheme, eachRRH is assigned a different spectral range). Moreover, it is appreciatedthat due to the relatively low transmission power of each RRH (typicalRRH transmit at approximately 20 dBm, as compared to an eNB whichtransmits at 43 dBm-49 dBm), a cell may be contain multiple RRHs whichare assigned to the same control region but which are sufficientlyseparated to avoid interference.

In a third aspect, it is appreciated that within each control region thephysical resource blocks (PRBs) assigned to each user can be furtherlogically permuted, so as to maximize frequency diversity for each user.More directly, such randomization ensures that the effects of anyinterferer that impacts only a few PRBs will be distributed among thepopulation of users serviced by that control region.

In a fourth aspect, the mobile device is notified of its associatedcontrol region. In one embodiment, a cell management entity determines(for at least a subset of its serviced population) an appropriatecontrol region for the mobile device. The cell management entity isfurther configured to update the associated control region as the mobiledevices move from RRH to RRH. Depending on certain mobilityconsiderations, the mobile device may be assigned to a particular RRH(e.g., for a designated number of transmission time intervals (TTI),etc.), or the eNB. For example, where a mobile device is quickly moving,the cell management entity may not assign the mobile device to a RRH atall. In contrast, where a mobile device is largely stationary, thecontrol entity may assign the mobile device to a RRH and/or a specificcontrol region for a large number of TTI.

Moreover, those of ordinary skill in the related arts will recognizethat unlike legacy schemes for control channel operation (e.g., seePrior Art Physical Downlink Control Channel (PDCCH)) which are based ona number of OFDM symbols at the start of each subframe, variousembodiments of the present invention may operate on varying degrees ofgranularity. For example, a control region for a mobile device can bespecified on a TTI basis, slot basis, subframe basis, frame basis, etc.The control channel overhead can be optimized according to variousnetwork considerations. For instance, where mobile device managementrequires significant control overhead, the network may switch to shortertime intervals for the control region(s) (e.g., slot basedtransmissions). In contrast, where control channel overhead is low, thenetwork may opt for longer time intervals (e.g., subframe basedtransmissions).

In a fifth aspect of the present invention, fine control over thecontrol region for each mobile device enables beamforming capabilities.As a brief aside, legacy control channel operation was limited to abroadcast of the control information over several symbols at the startof each subframe. Prior art mobile devices needed to: (i) decode thePhysical Control Format Indicator Channel (PCFICH), (ii) decode the cellspecific reference signals (CRS), (iii) perform channel estimation basedon the CRS, and (iv) decode the control symbols. In particular, the CRSis broadcast as a cell-specific signal, and is not device specific. Incontrast, various embodiments of the present invention can be configuredso as to use device specific reference signals with the appropriatecontrol region (e.g., demodulation reference signals (DM-RS)). Inparticular, the DM-RS of a specific control region are specific to aparticular device. This specificity can be leveraged by the network anddevice to adjust transmission and reception weights, so as to enablebeamforming of the device specific control channels.

At step 802, one or more control information for a population of devicesis determined. Common examples of control information include, withoutlimitation, scheduling information, operational information, formattinginformation, etc. For instance, scheduling information may include:resource requests, resource grants, resource allocations, etc. Typicalresources for use in wireless networks include: time slots, frequencybands, spreading codes, or any combination of the foregoing. Operationalinformation may include: supported features, non-supported features,identifying information (e.g., network identification, serving stationidentification, etc.). Formatting information may include: requests fora transport format, grants for a transport format, assignments to atransport format, etc. In one exemplary embodiment, resources are basedon a combination of time slots and frequency subcarriers.

In one exemplary embodiment, the control channel information isformatted for transmission as a Downlink Control Information (DCI)message. A DCI is generated based on a set of parameters that includes:the number of downlink Resource Blocks (RBs), the DCI format, etc.

At step 804, a suitable number of dynamically determined resources isdetermined for bearing at least a subset of the one or more controlinformation. Generally, control channel information is determined basedon current network activity and distributed to the population of devicesto optimize network performance. In one embodiment, the suitable numberof dynamically determined resources is based on a population of legacydevices. In other embodiments, the suitable number of dynamicallydetermined resources is based on the type of control information. Instill other embodiments, the number of dynamically determined resourcesis based on network configuration. Moreover, it is appreciated that insome embodiments, the dynamically determined resources are sufficientfor all control information.

Each of the at least subset of one or more control information isdynamically assigned to a resource at step 806. In one exemplaryembodiment, the one or more control information is assigned to aresource which is quickly identifiable by the receiving client device.Specifically, it may be desirable to limit the overall decoding burdenfor the client device. In some embodiments, the client device may berequired to try decoding multiple “hypotheses” which are stillsignificantly less than the entire bandwidth. By limiting thedistribution of control information to only a few hypotheses, a clientdevice can try each hypothesis to determine the location of controlchannel information.

For example, in one such variant, the frequency resources in each slotare partitioned into a number of Frequency Partitions (FP) where eachfrequency partition contains one or more control information regions.Each region consists of an integer number of physically consecutive orlogically consecutive resources. In some embodiments, each controlinformation region may be further associated with a transmitter of anetwork of transmitters. For example, in one exemplary embodiment, anenhanced Physical Downlink Control Channel (ePDCCH) region is associatedwith a Remote Radio Head (RRH) of a cellular network cell. Within theforegoing system, a client device does not have to search the entirespectral bandwidth to find the appropriate control information, ratherthe client device can quickly identify the appropriate controlinformation within the control region and decode it accordingly.

In one exemplary embodiment, the partitioning of resources is flexibleand can be dynamically configured, e.g., the resources may change overtime based on a cell-specific, semi-static or dynamic pattern. Forexample, the resource partitioning may be based on e.g., overall networkcomplexity, network capabilities, device capabilities, device populationsize, etc. Dynamic sizing can be used to support arbitrarily largepayloads; for example, within LTE networks flexible payload capabilitiescan accommodate larger format DCIs (e.g., Transmission Mode 9, etc.).Moreover, since the size of ePDCCH regions can be larger (or smaller),collisions across different cells and inter-cell interference can bemore effectively and flexibly mitigated.

In certain schemes, control information can be distributed over networkresources to maximize diversity techniques. For example, by permutingcontrol information (and in some cases redundant control information)throughout the available time and frequency ranges of resources,reception issues which affect certain resources (e.g., momentaryinterference that affects a time slot and/or subcarrier) can bemitigated. For example, in one exemplary embodiment an ePDCCH regioncontains one or more ePDCCH, where each ePDCCH is mapped to a number ofenhanced Control Channel Elements (eCCEs), and each eCCE is mapped toone or more Physical Resource Blocks (PRBs). The PRBs are distributed inboth time and frequency such that if one or more PRB is lost, theremaining PRBs can be used to reconstruct the ePDCCH.

Additionally, it is recognized that the flexible allocation of controlinformation can support features including soft frequency partitioningand/or Fractional Frequency Reuse (FFR) techniques. For instance,control information can be flexibly allocated across frequency to createconfigurable frequency partitions in control and data regions. Frequencypartitioning can be particularly useful for aggregated spectralresources (e.g., where the total network bandwidth is composed ofmultiple disparate frequency bands). For example, frequency partitioningcan provide control information over only a subset of the aggregatedbandwidth, where the client device does not have to receive the entireaggregated spectrum to determine the control information. Additionally,frequency control can be used to control the amount of power distributedfor providing data and control. For example, in prior art LTE networks,the PDCCH was transmitted across the entire spectral bandwidth, thus achange to power would affect the entire bandwidth. Various embodimentsof the present invention can increase transmit power for only thecontrol region of the ePDCCH.

One benefit to providing configurable control information is thatcontrol information does not have to be broadcast over the entire cell.In particular, control information need only be transmitted within therelative vicinity of the applicable user. For this reason, rather thanbroadcasting control information for all devices within the cell,various embodiments of the present invention are particularly useful forimplementing user-specific control information. In one exemplaryembodiment, a RRH only transmits control information which is applicablefor its set of serviced subscribers. This can contribute greatly tooverall network resource utilization.

Additionally, certain user-specific functionalities can be leveraged forfurther improvements. For instance, the control information may beprovided to the subscriber in conjunction with user-specific referencesignals. For example, in one exemplary embodiment, the ePDCCH isprovided in conjunction with Demodulation Reference Signals (DM-RS) toassist in channel estimation and coherent detection for a specificsubscriber device. Each user-specific DM-RS can be additionallybeamformed for the specific user. During beamforming, the transmittermodifies the transmission power from each antenna so as toconstructively interfere at a target receiver, and in some casesreducing interference for unintended receivers. Beamforming DM-RS cangreatly improve channel estimates, etc.

In still another embodiment, control information can be provided tousers based on the finest data granularity provided by thecommunications network. For example, within LTE networks, the smallestincrement of data transmission is the Physical Resource Block PRB). EachPRB is approximately 2% of the bandwidth resources for a 10 MHz system,and only 1% in a 20 MHz system. Providing higher granularity controlresources can reduce underutilization of network resources. Consider aprior art LTE network that could only allocate one, two or three OFDMsymbols for control data (e.g., 7%, 14%, and 21% of network resources,respectively), if the PDCCH exceeds the capacity of one OFDM symbol,then the PDCCH is stepped to the next increment. If only marginally moreinformation was transmitted, then the bulk of that newly allocated OFDMsymbol is wasted. In contrast, exemplary embodiments of the presentinvention may simply allocate the additional PRBs necessary to provisionthe additional ePDCCH information.

Referring back to FIG. 8, at step 808, the one or more controlinformation is transmitted according to the assigned resources. In oneexemplary embodiment, the control information is transmitted frommultiple transmission points, where the transmission point need not haveidentical transmission schedules for the control information. Forexample, within a cellular network, multiple Remote Radio Heads (RRHs)may each transmit control information according to individually distinctschedules.

Myriad other schemes for implementing dynamic allocation of resourceswill be recognized by those of ordinary skill given the presentdisclosure.

It will be recognized that while certain aspects of the invention aredescribed in terms of a specific sequence of steps of a method, thesedescriptions are only illustrative of the broader methods of theinvention, and may be modified as required by the particularapplication. Certain steps may be rendered unnecessary or optional undercertain circumstances. Additionally, certain steps or functionality maybe added to the disclosed embodiments, or the order of perfoiivance oftwo or more steps permuted. All such variations are considered to beencompassed within the invention disclosed and claimed herein.

While the above detailed description has shown, described, and pointedout novel features of the invention as applied to various embodiments,it will be understood that various omissions, substitutions, and changesin the form and details of the device or process illustrated may be madeby those skilled in the art without departing from the invention. Theforegoing description is of the best mode presently contemplated ofcarrying out the invention. This description is in no way meant to belimiting, but rather should be taken as illustrative of the generalprinciples of the invention. The scope of the invention should bedetermined with reference to the claims.

1-20. (canceled)
 21. A digital processor configured to: determine one ormore frequency partitions of a frequency resource, where the number ofthe frequency partitions is dynamically configured based on a parameterof a wireless network, and each frequency partition contains one or morecontrol channel regions, and each control channel region comprises alogical mapping of resource blocks and a scalable size, wherein thescalable size of each control channel region is dependent on a frequencyrange of the frequency resource; identify at least one control channelregion of the one or more control channel regions for receiving controlchannel information; and extract control channel information from theidentified at least one control channel region based on the logicalmapping of resource blocks, wherein the logical mapping of resourceblocks is permuted over a plurality of physical resource blocks, thephysical resource blocks being distributed in both time and frequency.22. The digital processor of claim 1, wherein, the digital processor isfurther configured to: when one of the plurality of physical resourceblocks is lost during transmission, the control channel regionscorresponding to the lost one of the plurality of physical resourceblocks are determined based on the one or more remaining physicalresource blocks.
 23. The digital processor of claim 21, wherein thedetermination of the one or more frequency partitions is performeddynamically.
 24. The digital processor of claim 21, wherein theextracted control channel information comprises one or more referencesignals specific to the wireless device.
 25. The digital processor ofclaim 21, wherein the identification of the at least one control channelregion is based at least on a message received from the wirelessnetwork.
 26. The digital processor of claim 21, wherein the digitalprocessor is one of a digital signal processor, a microprocessor, afield-programmable gate array, or plurality of processing componentsmounted on one or more substrates.
 27. A digital processor configuredto: dynamically partition one or more frequency resources into a numberof frequency partitions based on a parameter of a wireless network,where each frequency partition contains one or more control channelregions, and each control channel region comprises a logical mapping ofresource blocks and a scalable size, wherein the scalable size of eachcontrol channel region is dependent on a frequency range of the one ormore frequency resources; associate one or more wireless devices to atleast one control channel region of the one or more control channelregions; assign the identified at least one control channel region toone or more remote radio entities; and transmit control information forthe associated one or more wireless devices, wherein the logical mappingof resource blocks is permuted over a plurality of physical resourceblocks, the physical resource blocks being distributed in both time andfrequency.
 28. The digital processor of claim 27, wherein, when one ofthe plurality of physical resource blocks is lost during transmission,the control channel regions corresponding to the lost one of theplurality of physical resource blocks are determined based on the one ormore remaining physical resource blocks.
 29. The digital processor ofclaim 27, wherein the logical mapping of resource blocks is dynamicallydetermined.
 30. The digital processor of claim 27, wherein: the one ormore remote radio entities are geographically distinct; and theassociating of one or more wireless devices to the identified at leastone control channel region is based at least in part on a location ofthe one or more wireless devices.
 31. The digital processor of claim 27,wherein the one or more remote radio entities share a common identifier.32. The digital processor of claim 27, wherein the digital processor isfurther configured to: permute the logical mapping over a number oftransmissions.
 33. The digital processor of claim 27, wherein thedigital processor is further configured to: identify a corresponding oneof the one or more control channel regions for transmitting controlchannel information; and determine control information based on thelogical mapping of resource blocks.
 34. The digital processor of claim33, wherein the determining the control information further comprises:receiving only a portion of an aggregated spectrum to determine thecontrol information, wherein the control information is then providedover a subset of an aggregated bandwidth.
 35. The digital processor ofclaim 27, wherein the digital processor is one of a digital signalprocessor, a microprocessor, a field-programmable gate array, orplurality of processing components mounted on one or more substrates.36. A method, comprising: determining one or more frequency partitionsof a frequency resource, where the number of the frequency partitions isdynamically configured based on a parameter of a wireless network, andeach frequency partition contains one or more control channel regions,and each control channel region comprises a logical mapping of resourceblocks and a scalable size, wherein the scalable size of each controlchannel region is dependent on a frequency range of the frequencyresource; identifying at least one control channel region of the one ormore control channel regions for receiving control channel information;and extracting control channel information from the identified at leastone control channel region based on the logical mapping of resourceblocks, wherein the logical mapping of resource blocks is permuted overa plurality of physical resource blocks, the physical resource blocksbeing distributed in both time and frequency.
 37. The method of claim36, further comprising: when one of the plurality of physical resourceblocks is lost during transmission, the control channel regionscorresponding to the lost one of the plurality of physical resourceblocks are determined based on the one or more remaining physicalresource blocks.
 38. The method of claim 36, wherein the determinationof the one or more frequency partitions is performed dynamically. 39.The method of claim 36, wherein the extracted control channelinformation comprises one or more reference signals specific to thewireless device.
 40. The method of claim 16, wherein the identificationof the at least one control channel region is based at least on amessage received from the wireless network.